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Cuzzupino

macrumors newbie
Original poster
Jun 20, 2018
25
2
Hi,

I have a Mac Pro 5,1 mid 2010 with GTX 980 TI flashed. Sometimes I got black screen at boot... then the cpu fan go at full speed and the mac won't display anythings...

This is happen frequently when I run windows 10 for some hours and then switch back to mac...

To resolve this problem every time I need to disconnect and reconnect the GPU in pcie slot 16x and reconnect PCIE AUX power cable... then reboot and get the boot screen.

It is strange because this problem happen to me also with external PSU that power the card...

What can be the problem? CPU?
 

Synchro3

macrumors 68000
Jan 12, 2014
1,987
850
Do you use in Windows the Boot Camp control panel choosing MacOS as start volume before restarting?

Try not using the Boot Camp control panel in Windows, just restart, and use the Alt button for selecting an operating system during startup.

Option boot works also if your MacOS volume is APFS formatted.
 

Cuzzupino

macrumors newbie
Original poster
Jun 20, 2018
25
2
No i'm restarting normaly.. it would happen at random... now I reinstall windows 10, reinstall driver and switch the gpu to PCIE second slot 16x... I run windows over 3 hours with intensive graphic use then restart end no problem. I try to restart in all the and all seems work fine.

I need to test it for more time... I let You know.

Can it be a problem related to pcie 16x connector first slot?
 

Synchro3

macrumors 68000
Jan 12, 2014
1,987
850
I my case I have to use Option boot to return to macOS from Windows. Choosing macOS in the Boot Camp control panel doesn't work.

I think it has nothing to do with the graphics card/pcie 16x connector first slot.
 

Cuzzupino

macrumors newbie
Original poster
Jun 20, 2018
25
2
Try to explane better the situation...

I use Windows 10 and MAC OSX and I run fine in every situations, running benchmark of all types with good scores, passing all stress test also with direct x12 in 3D MARK (Time Spy test), in windows and in mac osx... the only one big problem is that at certain point when I go to power up the mac pro I get a black screen... and if I go to force restart I got black screen again... so when happen the first time there is no way to boot again...

I think that is a power issue because after days of several test seems that the problem gone away when I connect the VGA with use of an external PSU and not over only if I connect the VGA in the 2nd PCIEx16 slot.

I try every types of connections to power the VGA with only use of internal PSU because it should be able to handle 250W TDP and with every setup at first boot everything run good, I can run benchmark and play also games for hours... no problem... but at other reboots from windows or from mac osx also (often at second reboot) the black screen comes up and I need to use external PSU again to return to boot normally...

It is possible that the PSU is too old and deliver less wattage?
 

Cuzzupino

macrumors newbie
Original poster
Jun 20, 2018
25
2
I got black screen at startup again also with the external psu... I try to reboot but the black screen persist... I try to resetting pram and nvram and notthing.. I try to reset smc and notthing... I remove the optical and an ssd in the second cable of optical bay try to start always black screen... then I try to remove the only 3,5" original APPLE HDD that I use and magically the mac boot normally and black screen is gone... this is my experience and I don't know what to think... someone can help me?
 
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